Tìm x:
a)2lxl-lxl-5=-1 b)5-(10-x)=7 c)-12+(x-9)=0
Tìm x:a) x - 2 + 7 = 1 . 3 . -9
b) 4 . x - 1 = (-5) 5 12 2 4 16 9 2 9
c) -2 . x + 5 = 7
d) 2 . x : 7 . 1 = 29 3 8 12 5 3 8 15
Tìm x:a) x - 2 + 7 = 1 . 3 . -9
b) 4 . x - 1 = (-5) 5 12 2 4 16 9 2 9
c) -2 . x + 5 = 7
d) 2 . x : 7 . 1 = 29 3 8 12 5 3 8 15
Bài 1: Tìm x:a) x - 2 + 7 = 1 . 3 . -9 b) 4 . x - 1 = (-5) 5 12 2 4 16 9 2 9c) -2 . x + 5 = 7 d) 2 . x : 7 . 1 = 29 3 8 12 5 3 8 15Bài 2: Tính:a) 2 + 1 . 4 b) 0,8 : [ 4 . 1,25] - [ 0,64 - 1 ] 5 7 5 25--------------------- 8 - 1 : 3 2 5 c) 8 : [ 7 - 12 ] d) ( 1,08 - 2 ) : 4 + ( 59 - 13 ). 36 9 2 7 25 7 9 4 17----------------------- [ 5 - 1 ] : 4
Bài 1: Tìm x:a) x - 2 + 7 = 1 . 3 . -9 b) 4 . x - 1 = (-5) 5 12 2 4 16
Bài 1: Tìm x:a) x - 2 + 7 = 1 . 3 . -9
b) 4 . x - 1 = (-5) 5 12 2 4 16 9 2 9
c) -2 . x + 5 = 7
d) 2 . x : 7 . 1 = 29 3 8 12 5 3 8 15
Bài 2: Tính:
a) 2 + 1 . 4
b) 0,8 : [ 4 . 1,25] - [ 0,64 - 1 ] 5 7 5 258 - 1 : 3 2 5
c) 8 : [ 7 - 12 ]
d) ( 1,08 - 2 ) : 4 + ( 59 - 13 ). 36 9 2 7 25 7 9 4 17
Tìm x:
a, (x - 1/2) : 1/3 + 5/7 = 9 5/7
b, x + 30% x = - 1,31
c, -2/3.x + 1/5 = 1/10
\(a,\left(x-\dfrac{1}{2}\right):\dfrac{1}{3}+\dfrac{5}{7}=9\dfrac{5}{7}\)
\(\Leftrightarrow\left(x-\dfrac{1}{2}\right).3=\dfrac{68}{7}-\dfrac{5}{7}\)
\(\Leftrightarrow\left(x-\dfrac{1}{2}\right).3=9\)
\(\Leftrightarrow x-\dfrac{1}{3}=3\)
\(\Leftrightarrow x=3+\dfrac{1}{3}\)
\(\Leftrightarrow x=\dfrac{9}{3}+\dfrac{1}{3}\)
\(\Leftrightarrow x=\dfrac{10}{3}\)
\(b,x+30\%x=-1,31\)
\(\Leftrightarrow x+\dfrac{3}{10}.x=-\dfrac{131}{100}\)
\(\Leftrightarrow x.\left(1+\dfrac{3}{10}\right)=-\dfrac{131}{100}\)
\(\Leftrightarrow x.\dfrac{13}{10}=-\dfrac{131}{100}\)
\(\Leftrightarrow x=-\dfrac{131}{100}.\dfrac{10}{13}\)
\(\Leftrightarrow x=-\dfrac{131}{130}\)
\(c,-\dfrac{2}{3}x+\dfrac{1}{5}=\dfrac{1}{10}\)
\(\Leftrightarrow\dfrac{-2}{3}x=\dfrac{1}{10}-\dfrac{1}{5}\)
\(\Leftrightarrow\dfrac{-2}{3}x=\dfrac{1}{10}-\dfrac{2}{10}\)
\(\Leftrightarrow-\dfrac{2}{3}x=-\dfrac{1}{10}\)
\(\Leftrightarrow x=-\dfrac{1}{10}.\left(-\dfrac{3}{2}\right)\)
\(\Leftrightarrow x=\dfrac{3}{20}\)
Bài 1 : Tìm x thuộc Z
a) lxl = 11
b) lxl = 0
c) lxl = -7
d) lxl = -14
e) -12lxl = -36
g) lxl = 5 và x<0
a)11 hoặc -11
b)0
c)không tồn tại
d)không tồn tại
e)-3 hoặc 3
g)-5
a)x=11;-11
b)x=0
c)x=-7;7
d)x=14;-14
e)x=3;-3
g)x=-5
a)x=+-5
b)x=0
c)x=-7
d)x=-14
e)x=+-3
g)x=-5
Tìm x:
a)(x+3)2-4x-12=0
b)x(x+5)(x-5)-(x-3)(x2+3x+9)=7
a) (x + 3)^2 - 4x - 12 = 0
<=> (x + 3)^2 - 4(x + 3) = 0
<=> (x + 3)(x - 1) = 0
<=> x = -3 hoặc x = 1
b) x(x + 5)(x- 5) - (x - 3)(x^2 + 3x + 9) = 7
<=> x^3 - 25x - x^3 + 27 = 7
<=> -25x + 27 = 7
<=> x = 4/5
a/ \(\left(x+3\right)^2-4x-12=0\)
\(\left(x+3\right)^2-4\left(x+3\right)=0\)
\(\left(x+3\right)\left(x+3-4\right)=0\)
\(\left[{}\begin{matrix}x+3=0\Rightarrow x=-3\\x+3-4=0\Rightarrow x=1\end{matrix}\right.\)
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b/ \(x\left(x+5\right)\left(x-5\right)-\left(x-3\right)\left(x^2+3x+9\right)=7\)
\(x\left(x^2-25\right)-\left(x^3-27\right)=7\)
\(x^3-25x-x^3+27=7\)
\(-25x=-20\)
\(x=\dfrac{20}{25}=\dfrac{4}{5}\)
a, <=>x2 +6x+9-4x-12=0
<=> x2 +2x -3=0
<=> x2 +3x -x-3=0
<=> x.(x+3) - (x+3) =0
<=> (x-1)(x+3)=0
<=> x=1 hoặc x=-3
b, <=> x(x2 -25) - (x-3)(x+3)2 -7=0
<=> x3 -25x + (9-x2) (x+3) -7=0
<=> x3 -25x+ 9x+27-x3 -3x2 -7=0
<=> -3x2 -16x +20=0
<=>(3x-10)(x-2) =0 (đoạn này tự phân tích nha ^ ^)
<=> x= 10/3 hoặc x=2
Chúc bạn học tốt nha!